The process of myelopoiesis in guinea pigs under conditions of a static magnetic field

Myelopoiesis and distribution of white blood cells in peripheral blood in 210 guinea pigs related to the duration and induction of an applied magnetic field were studied. Exposure to a static magnetic field of induction 0.05 T and 0.3 T each day for 7 weeks at 1 h per day led to a decrease of basophilic and polychromatophilic erythroblasts, an increase in the percentage of cells of the granulopoietic (neutrophilic myelocytes, eosinophilic metamyelocytes, band neutrophils, band basophils, segmented eosinophils) and lymphopoietic system, a slight increase in plasma cells and decrease in the percentage of megakaryocytes in bone-marrow. In the peripheral blood the percentage of lymphocytes was increased. The observed changes were independent on the duration of magnetic field action within the magnetic induction value.     

Effect of magnetic field on the process of cell respiration in mitochondria of rats

Exposure of rats to static magnetic field 1 hour daily for a period of 7 weeks (7 days a week) leading to disturbances of the respiration processes in the mitochondria of liver cells. The rate of respiration through NADH dehydrogenase, succinic dehydrogenase and cytochrome oxidase was dependent on both the duration and the intensity value of the field applied. The animals showed greater sensitivity to the action of a 0.008 T magnetic induction field than to that of 0.15 T. The observed changes were reversible after 3 months since the everyday exposure had been stopped.     

Fibrinolytical processes in rabbits activated by the magnetic field

Rabbits were exposed to a constant magnetic field of 0.005 T, 0.1 T and 0.3 T induction for one hour per day each day for a period of four weeks. It was found that the magnetic field increases the rate of fibrinolytical processes. A decrease in fibrinogen concentration, an increase in the level of fibrinogen degradation products and a considerably shorter time of fibrinolysis in plasma were all noted. The magnitude of these processes was proportional to duration of exposure to the magnetic field in action. These date confirms the similar effect observed in other mammalians (guinea pigs, rats). Thus, the application of a static magnetic field of intensity as low as 0.005 T to increase a fibrinolytical processes in the thrombotic therapy seems to be justified.     

The effect of electromagnetic field on reactive oxygen species production in human neutrophils in vitro

The present study was undertaken in order to determine the effect of low frequency electromagnetic field (EMF) on reactive oxygen species (ROS) production in human neutrophils in peripheral blood in vitro. We investigated how differently generated EMF and several levels of magnetic induction affect ROS production. To evaluate the level of ROS production, two fluorescent dyes were used: 2′7′-dichlorofluorscein-diacetate and dihydrorhodamine. Phorbol 12-myristate 13-acetate (PMA), known as strong stimulator of the respiratory burst, was also used. Alternating magnetic field was generated by means of Viofor JPS apparatus. Three different levels of magnetic induction have been analyzed (10, 40 and 60 μT). Fluorescence of dichlorofluorescein and 123 rhodamine was measured by flow cytometry. The experiments demonstrated that only EMF tuned to the calcium ion cyclotron resonance frequency was able to affect ROS production in neutrophils. Statistical analysis showed that this effect depended on magnetic induction value of applied EMF. Incubation in EMF inhibited cell activity slightly in unstimulated neutrophils, whereas the activity of PMA-stimulated neutrophils has increased after incubation in EMF.     

Effect of chronic exposure to static magnetic field upon the K+, Na+ and chlorides concentrations in the serum of guinea pigs

The magnetic field influence on the concentration of serum K+, Na+ and chlorides was tested. The guinea pigs were exposed to the static magnetic field for six weeks 1 hour a day, 7 days a week. Magnetic field of induction 0.005 T--0.3 T produced progressively an increase in Na+ concentration and a decrease in chlorides concentration in the serum. The range of observed changes was dependent on the duration of exposure to the magnetic field. No change in K+ serum concentration was observed following magnetic field exposure.     

Effect of constant magnetic field on the liver of guinea pig. Electron microscopic studies.

Twenty guinea pigs were exposed 1 hour daily, for 3 to 7 weeks to constant magnetic field (CMF), the induction of which was 0.005 T, and 0.3 T. Hepatocytes were examined in semithin sections with light microscope and TEM. The negative photographic plates of the TEM were analyzed and measured with densitometer. It was shown that CMF of the induction 0.005 T and 0.3 T exhibited structural changes in hepatocytes, primarily in mitochondria.     

Lack of a co-promotion effect of 60 Hz rotating magnetic fields on N-ethyl-N-nitrosourea induced neurogenic tumors in F344 rats

The present study was conducted to investigate the possible effect of 60 Hz magnetic fields as promoters of brain tumors initiated transplacentally by ethylnitrosourea (ENU) in F344 rats. One hundred twenty mated animals were divided into six different groups and exposed in utero on day 18 of gestation to a single intravenous dose of either Saline (vehicle control, Group I), or ENU 10 mg/kg (Groups II-VI). In the present study, a total of 480 offspring was used. The offspring in group II were given no further treatment while the offspring in Groups III-VI were exposed to four different intensities of magnetic fields. Animals received exposure to 60 Hz magnetic field at field strengths of 0 Tesla (sham control, T1, Group III), 5 muT (T2, Group IV), 83.3 muT (T3, Group V), or 500 muT (T4, Group VI), for 21 h/day from the age of 4 weeks to the age of 32 or 42 weeks. At histopathological examination, tumors of the nervous system were seen in all the ENU-treated groups. The tumor incidence of the ENU group at 32nd and 42nd week necropsy was higher than that of the vehicle control group. The incidence of glial tumors at 42nd week necropsy was higher than the 32nd week necropsy. However, there were no differences in the tumor incidence between the sham control (T1) and ENU + magnetic field exposure groups (T2-T4). In conclusion, there was no evidence that exposure of offspring to 60 Hz at magnetic field strengths up to 500 muT to the age of 32 or 42 weeks promoted ENU-initiated brain tumors in rats.     

Thermostability of the erythrocytes of mice exposed to the action of a magnetic field.

The authors investigated the thermostability of the erythrocytes os strain CBA mice exposed to the action of a magnetic field formed by the poles of a rotating permanent magnet of 20 mT (200 GAUSS) induction. The erythrocytes of animals which spent 17 weeks in the magnetic field were significantly less heat resistance than those of the control animals. The effect on animals kept in the magnetic field during embryoyenesis and infancy and then left 3 months outside it was even more pronounced.     

Effect of chronic exposure to static magnetic field upon the serum glutamic pyruvic transaminase activity GPT and morphology of the cardiac muscle, skeletal muscles, kidneys, cerebellum and lung tissue in guinea pigs

In a cycle of investigations concerning the pathogenesis of functional changes caused by the influence of magnetic field of induction occurring in laboratory and industrial conditions glutamic pyruvic transaminase activity in external blood and morphological picture of cardiac muscle, skeletal muscles, kidneys, cerebellum and lung tissue in guinea pigs were examined. Static homogeneous magnetic field as low as 0.005 T produced a statistically significant decrease in GPT activity. The animals were exposed to the magnetic field action for seven weeks 1 hour a day, 7 days a week. The range of observed changes of enzyme activity were determined by the duration of magnetic field. No morphological changes were observed.     

Influence of strong static magnetic fields on primary cortical neurons

Intense uniform magnetic fields, such as those used in magnetic resonance imaging (MRI), are thought to exert little influence at the cellular level. Here we report modifications of the signaling cascades in rat cortical neurons cultured for 1 h in magnetic fields of up to 5 Tesla. The activation of c-Jun N-terminal kinase (JNK) increases monotonically with field strength, with a maximal activation of approximately 10% at 5 T, whereas the activation of extra cellular-regulated kinase (ERK) shows a maximum at 0.75 T ( approximately 10%). Since ERK is involved in cellular differentiation, these results indicate a magnetic induction of the signaling events associated with differentiation. However, the cells respond to further increases in field strength by evoking a stress response, since JNK is a stress-activated protein kinase. Three possible mechanisms are discussed and of these, the most plausible is magnetic field induced change in the membrane rest potential, a microscale magnetohydrodynamic effect. This mechanism most likely involves the activation of voltage dependent Ca(2+) channel opening; since intracellular Ca(2+) concentration was also found to be modified by the static magnetic field.     

Total antioxidant capacity, total oxidant status and oxidative stress index in the men exposed to 1.5 T static magnetic field

The aim of this study was to investigate the effects of a high-strength magnetic field produced by a magnetic resonance imaging (MRI) apparatus on oxidative stress. The effects of a 1.5 T static magnetic field on the total antioxidant capacity (TAC), total oxidant status (TOS) and oxidative stress index (OSI) in male subjects were investigated. In this study, 33 male volunteers were exposed to a 1.5 T static magnetic field for a short time and the TAC, TOS and OSI of each subject were determined. Magnetic field exposure was provided using a magnetic resonance apparatus; radiofrequency was not applied. Blood samples were taken from subjects and TAC, TOS and OSI values were measured using the methods of Erel. TAC showed a significant increase in post-exposures compared to pre-exposures to the magnetic field (p < 0.05). OSI and TOS showed a significant decrease in post-exposures compared to pre-exposures to a 1.5 T magnetic field (for each of two, p < 0.01). The 1.5 T static magnetic field used in the MRI apparatus did not yield a negative effect; on the contrary, it produced the positive effect of decreasing oxidative stress in men following short-term exposure.     

Effect of a low-frequency magnetic field on systemic arterial pressure in spontaneously hypertensive rats

The effect of low-frequency magnetic field (MF) on systemic blood pressure has been studied in chronic experiments on 21 spontaneously hypertensive rats. The animals' kidney area was exposed to MF (induction value 30T). Direct blood pressure measurements have revealed an antihypertensive effect.     

Effect of magnetic field on food and water intake and body weight of spinal cord injured rats

Chronic (2 h/d x 8 weeks) exposure to magnetic field (MF; 50 Hz, 17.9 microT) in complete spinal cord (T13) transected rats restored food intake (FI), water intake (WI) and body weight (BW) which were decreased in the spinal cord injured rats. The results suggest a significant beneficial effect of chronic exposure to magnetic field of paraplegic rats.     

Weak extremely-low-frequency magnetic field-induced regeneration anomalies in the planarian Dugesia tigrina

We recently reported that cephalic regeneration in the planarian Dugesia tigrina was significantly delayed in populations exposed continuously to combined parallel DC and AC magnetic fields. This effect was consistent with hypotheses suggesting an underlying resonance phenomenon. We report here, in a parallel series of investigations on the same model system, that the incidence of regeneration anomalies presenting as tumor-like protuberances also increases significantly (P < .001) in association with exposure to weak 60 Hz magnetic fields, with peak intensities ranging between 1.0 and 80.0 μT. These anomalies often culminate in the complete disaggregation of the organism. Similar to regeneration rate effects, the incidence of regeneration anomalies is specifically dependent upon the planaria possessing a fixed orientation with respect to the applied magnetic field vectors. However, unlike the regeneration rate effects, the AC magnetic field alone, in the absence of any measurable DC field, is capable of producing these anomalies. Moreover, the incidence of regeneration anomalies follows a clear dose-response relationship as a function of AC magnetic field intensity, with the threshold for induced electric field intensity estimated at 5 μV/m. The addition of either 51.1 or 78.4 μT DC magnetic fields, applied in parallel combination with the AC field, enhances the appearance of anomalies relative to the 60 Hz AC field alone, but only at certain AC field intensities. Thus, whereas our previous study of regeneration rate effects appeared to involve exclusively resonance interactions, the regeneration anomalies reported here appear to result primarily from Faraday induction coupling. These results together with those reported previously point to two distinct physiological effects produced in regenerating planaria by exposure to weak extremely-low-frequency (ELF) magnetic fields. They further suggest that the planarian, which has recently been identified elsewhere as an excellent system for use in teratogenic investigations involving chemical teratogens, might be used similarly in teratogenic investigations involving ELF magnetic fields. © 1996 Wiley-Liss, Inc.     

Alterations in the rat electrocardiogram induced by stationary magnetic fields

A field strength dependent increase in the amplitude of the T-wave signal in the rat electrocardiogram (ECG) was observed during exposure to homogeneous, stationary magnetic fields. For 24 adult Sprague-Dawley and Buffalo rats of both sexes, the T-wave amplitude was found to increase by an average of 408% in a 2.0 Tesla (1 Tesla = 10⁴ Gauss) field. No significant magnetically induced changes were observed in other components of the ECG record, including the P wave and the QRS complex. The minimum field level at which augmentation of the T wave could be detected was 0.3 Tesla. The magnetically induced increase in T-wave amplitude occurred instantaneously, and was immediately reversible after exposure to fields as high as 2.0 Tesla. No abnormalities in any component of the ECG record, including the T wave, were noted during a period of 3 weeks following cessation of a continuous 5-h exposure of rats to a 1.5-Tesla field. The heart rate and breathing rate of adult rats were not altered during, or subsequent to, application of fields up to 2.0 Tesla. The effect of animal orientation within the field was tested using juvenile rats 3–14 days old. The maximum increase in T-wave amplitude was observed when subjects were placed with the long axis of the body perpendicular to the lines of magnetic induction. These experimental observations, as well as theoretical considerations, suggest that augmentation of the signal amplitude in the T-wave segment of the ECG may result from a superimposed electrical potential generated by aortic blood flow in the presence of a stationary magnetic field.     

Influence of 60-hertz magnetic fields on leukemia

Female DBA/2 mice at 8 weeks of age were implanted with P388 leukemia cells in groups of ten mice and exposed to a 60-Hz 1.4-μT, 200-μT, or 500-μT magnetic field 2-3 hours after the implant for 6 hours daily, 5 days/week until all the exposed P388-treated and nontreated mice died. Parallel exposed groups of non-P388-treated mice and P388-treated mice exposed at 0 μT were included for study. No statistically significant differences (P > .05) in survival, spleen weight, or body weight resulted between P388-treated or nontreated mice from exposure to the magnetic field. No effect on the incidence or progression of P388 leukemia was apparent.     

Weak extremely-low-frequency magnetic fields and regeneration in the planarian Dugesia tigrina

Extremely-low-frequency (ELF), low-intensity magnetic fields have been shown to influence cell signaling processes in a variety of systems, both in vivo and in vitro. Similar effects have been demonstrated for nervous system development and neurite outgrowth. We report that regeneration in planaria, which incorporates many of these processes, is also affected by ELF magnetic fields. The rate of cephalic regeneration, reflected by the mean regeneration time (MRT), for planaria populations regenerating under continuous exposure to combined DC (78.4 μT) and AC (60.0 Hz at 10.0 μT _peak) magnetic fields applied in parallel was found to be significantly delayed (P ? 0.001) by 48 ± 1 h relative to two different types of control populations (MRT ? 140 ± 12 h). One control population was exposed to only the AC component of this field combination, while the other experienced only the ambient geomagnetic field. All measurements were conducted in a low-gradient, low-noise magnetics laboratory under well-maintained temperature conditions. This delay in regeneration was shown to be dependent on the planaria having a fixed orientation with respect to the magnetic field vectors. Results also indicate that this orientation-dependent transduction process does not result from Faraday induction but is consistent with a Ca²⁺ cyclotron resonance mechanism. Data interpretation also permits the tentative conclusion that the effect results from an inhibition of events at an early stage in the regeneration process before the onset of proliferation and differentiation. © 1995 Wiley-Liss, Inc.     

Effects of radiation and other influences on chemical lymphomagenesis

Methylnitrosourea (MNU) or butylnitrosourea (BNU) was used to induce T cell lymphomas (thymomas) in BDF1 mice. In addition to the chemical, X-rays in various dose schedules were applied. An effect of the irradiation (shortening of the latency period) was seen with 12 X 0.25 Gy in protocols with a prolonged median induction time in the controls as a result of a dose reduction of the chemical (median induction time 27-36 weeks instead of 16-18 weeks under 'optimal' conditions using 50 mg kg-1 of MNU). Preirradiation 2-5 weeks before 40 mg kg-1 of MNU resulted in enhanced leukaemogenesis. Also, mice with regenerating lympho-haemopoiesis after lethal irradiation and bone marrow transplantation were more sensitive to the effect of both chemicals than were the controls. Treatment with anti-thy 1.2 and with corynebacterium parvum during the latency period had no influence.     

The influence of spatial pulsed magnetic field application on neuropathic pain after tibial nerve transection in rat

The purpose of the study was to examine the influence of the spatial variable magnetic field (induction: 150–300?µT, 80–150?µT, 20–80?µT; frequency 40?Hz) on neuropathic pain after tibial nerve transection. The experiments were carried out on 64 male Wistar C rats. The exposure of animals to magnetic field was performed 1?d/20?min., 5?d/week, for 28?d. Behavioural tests assessing the intensity of allodynia and sensitivity to mechanical and thermal stimuli were conducted 1?d prior to surgery and 3, 7, 14, 21 and 28?d after the surgery. The extent of autotomy was examined. Histological and immunohistochemical analysis was performed. The use of extremely low-frequency magnetic fields of minimal induction values (20–80?µT/40?Hz) decreased pain in rats after nerve transection. The nociceptive sensitivity of healthy rats was not changed following the exposition to the spatial magnetic field of the low frequency. The results of histological and immunohistochemical investigations confirm those findings. Our results indicate that extremely low-frequency magnetic field may be useful in the neuropathic pain therapy.     

The effect of static magnetic field on protein concentration in serum of guinea-pigs

The influence of the static magnetic field on magnetic induction 0.005 T--0.3 T on the protein concentration in serum of guinea-pigs with regard of twenty four hours rhythm was investigated. The range of occurrenced changes were determined by the duration of the static homogeneous magnetic field.